1. Field of the Invention
This invention relates generally to apparatus and methods of removing fluids, sand, and debris from the bottom of well bores, and more particularly to a downhole well clean out tool reciprocally and rotatably connected in a drill string and having a bypass swab assembly within a pump barrel above a debris receiving and trapping sub to capture sand and debris in the sub and discharge fluids through apertures in the pump barrel.
2. Brief Description of the Prior Art
Sand pumps and cleanout tools which remove sand and debris from wells are known in the art. Wire line sand pumps are lowered into a well bore on a wire line and are operated by reciprocating the wire line to operate a piston rod. Wire line sand pumps have limited motion due to the flexible wire line. Other types of sand pumps utilize a rigid string extending from the surface to impart rotary and reciprocating movement to the pump apparatus. Some sand pump devices provide for returning the pumped fluids to the well and others remove it entirely from the well by pumping it to the surface. There are several patents which disclose various cleanout tools and downhole pump apparatus for removing sand and debris from the well bore.
McFarlane, U.S. Pat. No. 2,224,916 discloses a well swab having a cruciform cross sectioned mandrel with vertical channels and a shoulder at each end. The mandrel is installed above a check valve which has a port communicating with the channels. A swab sleeve having a metal liner and a rubber exterior packer slides on the mandrel and seats at the lower end to close the port.
Read, U.S. Pat. No. 3,352,212 discloses well swab sealing devices having a plurality of upwardly facing unreinforced rings or flanges molded in spaced relationship about a metal tubular support, and are arranged to flex downwardly under a load of fluid and to flex further downward under a predetermined load of fluid to allow the by-pass of fluid about the edges of the flexible sealing flanges to dump the excess load.
Hamrick, U.S. Pat. No. 4,407,360 discloses a water pump which utilizes an inflatable packer and a conical sand trap.
Moody et al, U.S. Pat. No. 4,421,182 discloses a hydraulic clean-out and drilling tool. The lower assembly includes a debris chamber and a flapper trap valve.
Caldwell, U.S. Pat. Nos. 4,478,285 and 4,711,299 disclose apparatus for removing debris which include a hollow piston with a splined piston rod keyed to the pumping portion to transmit rotary motion to the lower debris retaining portion. A hollow piston head includes a ball valve to prevent downward flow of fluid. Liquid debris is passed through the interior of the piston and into the upper portion of the apparatus. The upper portion of the apparatus selectively receives a ported sub for recirculating the liquid back into the well or an unported sub which prevents return of the debris to the well.
Williams et al, U.S. Pat. No. 4,493,383 discloses a well clean out tool utilizing an inverted modified Bowen bumper sub which includes a piston with a hollow hexagonal piston tube plugged at the upper end and keyed to the pumping sub to transmit rotary motion to the lower debris retaining portion. The hollow piston includes a valve to control flow of fluid into the bore of the piston and piston tube and a plurality of unrestricted openings through the hollow wall of the piston and closely adjacent to the valve.
The present invention is distinguished over the prior art in general, and these patents in particular by a well clean out tool installed in a drill string above one or more debris-receiving and trapping subs. A pumping portion includes an elongate pump barrel attached at its bottom end to the upper debris trapping sub and has a top cap at its upper end with a hexagonal opening. The upper portion of the pump barrel has apertures through its side wall. A hexagonal pump mandrel extends through the top cap and is connected to the bottom of the drill string by a top sub having apertures through its side wall whereby the pump barrel may be rotated with the drill string. A swab assembly contained within the pump barrel is connected to the bottom end of the pump mandrel and reciprocated thereby. The swab assembly includes a swab bypass mandrel having a cruciform cross section forming longitudinal fluid bypass channels with stop shoulders at each end. One or more swab cups having internal metal sleeves ride on the exterior of the bypass mandrel and allow fluid circulation through the bypass channels in an upper position and in the lower lifting position close off circulation through the bypass channels and form a sliding fluid sealing relation with the interior surface of the pump barrel. A mule shoe sub, notched collar, drag bit, mill, or other suitable device may be installed at the bottom of the debris trapping subs to break up and/or penetrate the sand and debris at the bottom of the well bore.
After the clean-out tool is fully extended and on the downstroke, the swab bypass mandrel moves down relative to the swab cups to allow passage of fluid through the bypass channels and the apertures in the pump barrel and the sub connecting the pump barrel to the drill string to prevent hydraulic action of fluid inside the pump barrel and allow the valves in the debris-receiving and trapping sub to close and capture sand and debris in the sub. When the pump apparatus is on the up stroke, the bypass mandrel moves up, and the lower swab cup engages the lower stop shoulder and closes off the bypass channels and forms a sliding fluid sealing relation with the pump barrel interior. As the swab assembly is raised relative to the pump barrel, the valves in the debris-receiving and trapping subs open allowing sand and debris to enter the debris-receiving and trapping subs and the fluids within the pump barrel are discharged out through the fluid outlets near the top portion of the pump barrel.